LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
FreeCAD - An open-source parametric 3D modeler
nanoCAD - nanoCAD is a pro-grade 2D CAD system with native DWG support and full customizability.
ECam - Nice, fast and intuitive. A 2D Cad/Cam designed for simple machining operation
Autodesk AutoCAD - Autodesk AutoCAD is a commercial computer-aided design (CAD) and drafting software application.
PyCAM - PyCAM is a toolpath generator for 3-axis CNC machining.